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NCERT Class 10 Science Life Processes: In-text questions (page 91) Solutions

Step-by-step working for every question of In-text questions (page 91) in NCERT's Class 10 Science book, chapter “Life Processes”, written by Shishya. Each question is in our own short words; open the NCERT chapter for the exact wording and figures.

1. In-text (page 91) Q1

   What advantage does a terrestrial organism have over an aquatic one in getting oxygen for respiration?

   1. Aquatic organisms must extract dissolved oxygen from water, which is present in low concentration.
   2. Terrestrial organisms breathe air, which contains a much higher percentage of oxygen than water.
   3. The gills of aquatic animals are designed to work against the low oxygen availability in water.
   4. Lungs of terrestrial animals are efficient at extracting oxygen from the air-rich medium.
   5. This difference allows terrestrial organisms to meet their oxygen demands more easily than aquatic ones.

   Answer: Terrestrial organisms have the advantage of breathing air, which contains a higher concentration of oxygen compared to the dissolved oxygen available in water for aquatic organisms.

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2. In-text (page 91) Q2

   In what different ways is glucose oxidised to give energy in different organisms?

   1. Glucose is oxidised to release energy through a process called cellular respiration.
      why?

      Oxidation is gain of oxygen (or loss of hydrogen); reduction is loss of oxygen (or gain of hydrogen). In a redox reaction one substance is oxidised while another is reduced.

   2. In the presence of oxygen, glucose is completely broken down into carbon dioxide and water, releasing a large amount of energy.
   3. This process is called aerobic respiration and occurs in the mitochondria of cells.
   4. In the absence of oxygen, glucose is incompletely broken down into lactic acid or ethanol and carbon dioxide, releasing less energy.
   5. This process is called anaerobic respiration and occurs in the cytoplasm of cells.
   6. Most organisms, including humans, use aerobic respiration to obtain energy from glucose.
   7. Some organisms, like yeast and certain bacteria, use anaerobic respiration to produce energy when oxygen is not available.

   Answer: Glucose is oxidised aerobically in the presence of oxygen to produce carbon dioxide, water, and energy, or anaerobically in the absence of oxygen to produce lactic acid or ethanol, carbon dioxide, and less energy.

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3. In-text (page 91) Q3

   How are oxygen and carbon dioxide transported in human beings?

   1. Oxygen is transported by the blood, specifically by the red blood cells.
   2. Each red blood cell contains a protein called haemoglobin which binds to oxygen.
   3. The oxygen-haemoglobin complex carries oxygen from the lungs to the body's tissues.
   4. Carbon dioxide is transported in the blood in three different forms.
   5. Most carbon dioxide travels as bicarbonate ions in the plasma.
   6. Some carbon dioxide is carried as a carbaminohaemoglobin complex with haemoglobin.
   7. A small amount of carbon dioxide dissolves directly in the plasma.
   8. The blood carries carbon dioxide from the tissues back to the lungs for exhalation.

   Answer: Oxygen is transported by haemoglobin in red blood cells, while carbon dioxide is transported as bicarbonate ions, carbaminohaemoglobin, and dissolved in plasma.

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4. In-text (page 91) Q4

   How are human lungs designed to maximise the area for gas exchange?

   1. The human lungs are designed to maximize the surface area for gas exchange through a highly branched structure.
   2. Inside each lung, there are millions of tiny air sacs called alveoli.
   3. These alveoli are surrounded by a dense network of capillaries.
   4. The thin walls of the alveoli and capillaries allow gases to diffuse easily.
   5. This arrangement provides a very large surface area for the exchange of oxygen and carbon dioxide.

   Answer: The lungs contain millions of alveoli surrounded by capillaries, providing a large surface area for efficient gas exchange.

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